Fingerprint recognition has a number of important, attractive and desirable attributes. No two individuals have the same fingerprint. In addition, details in each fingerprint are permanent and do not change over time.
Present-day fingerprint sensors can be broadly classified into one of the three main technologies: optical, ultrasound and solid state. Each of these sensors has their advantages and drawbacks. Optical and ultrasound sensors usually require more complicated mechanical parts and therefore, they usually are bulkier in size and more expensive to produce. Solid state sensors, on the other hand, are lower in cost and more compact.
Solid state sensors to date are based on capacitive, thermal, piezoelectric and electric field technologies. A major drawback of currently available solid state sensors is their inability to consistently capture a fingerprint image with a sufficiently good signal-to-noise ratio (SNR).